Commit 2ea572a8 authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r348181: 

------------------------------------------------------------------------
r348181 | lebedevri | 2018-12-03 12:07:58 -0800 (Mon, 03 Dec 2018) | 8 lines

[InstCombine] foldICmpWithLowBitMaskedVal(): disable 2 faulty folds.

These two folds are invalid for this non-constant pattern
when the mask ends up being all-ones:
https://rise4fun.com/Alive/9au
https://rise4fun.com/Alive/UcQM

Fixes https://bugs.llvm.org/show_bug.cgi?id=39861
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llvm-svn: 348528
parent a0f6a343

llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

+4 −0
Original line number Diff line number Diff line
@@ -2924,12 +2924,16 @@ static Value *foldICmpWithLowBitMaskedVal(ICmpInst &I, 
    //  x & (-1 >> y) s>= x    ->    x s<= (-1 >> y)

    if (X != I.getOperand(1)) // X must be on RHS of comparison!

      return nullptr;         // Ignore the other case.

    if (!match(M, m_Constant())) // Can not do this fold with non-constant.

      return nullptr;

    DstPred = ICmpInst::Predicate::ICMP_SLE;

    break;

  case ICmpInst::Predicate::ICMP_SLT:

    //  x & (-1 >> y) s< x    ->    x s> (-1 >> y)

    if (X != I.getOperand(1)) // X must be on RHS of comparison!

      return nullptr;         // Ignore the other case.

    if (!match(M, m_Constant())) // Can not do this fold with non-constant.

      return nullptr;

    DstPred = ICmpInst::Predicate::ICMP_SGT;

    break;

  case ICmpInst::Predicate::ICMP_SLE:

llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sge-to-icmp-sle.ll

+6 −4
Original line number Diff line number Diff line
@@ -26,8 +26,9 @@ define i1 @p0(i8 %x) { 
define i1 @pv(i8 %x, i8 %y) {

; CHECK-LABEL: @pv(

; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]

; CHECK-NEXT:    [[TMP1:%.*]] = icmp sge i8 [[TMP0]], [[X:%.*]]

; CHECK-NEXT:    ret i1 [[TMP1]]

; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[TMP0]], [[X:%.*]]

; CHECK-NEXT:    [[RET:%.*]] = icmp sge i8 [[TMP1]], [[X]]

; CHECK-NEXT:    ret i1 [[RET]]

;

  %tmp0 = lshr i8 -1, %y

  %tmp1 = and i8 %tmp0, %x
@@ -120,8 +121,9 @@ define i1 @cv0(i8 %y) { 
; CHECK-LABEL: @cv0(

; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()

; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]

; CHECK-NEXT:    [[TMP1:%.*]] = icmp sle i8 [[X]], [[TMP0]]

; CHECK-NEXT:    ret i1 [[TMP1]]

; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]

; CHECK-NEXT:    [[RET:%.*]] = icmp sge i8 [[TMP1]], [[X]]

; CHECK-NEXT:    ret i1 [[RET]]

;

  %x = call i8 @gen8()

  %tmp0 = lshr i8 -1, %y

llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-slt-to-icmp-sgt.ll

+6 −4
Original line number Diff line number Diff line
@@ -26,8 +26,9 @@ define i1 @p0(i8 %x) { 
define i1 @pv(i8 %x, i8 %y) {

; CHECK-LABEL: @pv(

; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]

; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt i8 [[TMP0]], [[X:%.*]]

; CHECK-NEXT:    ret i1 [[TMP1]]

; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[TMP0]], [[X:%.*]]

; CHECK-NEXT:    [[RET:%.*]] = icmp slt i8 [[TMP1]], [[X]]

; CHECK-NEXT:    ret i1 [[RET]]

;

  %tmp0 = lshr i8 -1, %y

  %tmp1 = and i8 %tmp0, %x
@@ -120,8 +121,9 @@ define i1 @cv0(i8 %y) { 
; CHECK-LABEL: @cv0(

; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()

; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]

; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt i8 [[X]], [[TMP0]]

; CHECK-NEXT:    ret i1 [[TMP1]]

; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]

; CHECK-NEXT:    [[RET:%.*]] = icmp slt i8 [[TMP1]], [[X]]

; CHECK-NEXT:    ret i1 [[RET]]

;

  %x = call i8 @gen8()

  %tmp0 = lshr i8 -1, %y